1. Field of the Invention
This invention relates to a synthetic resin product containing various substance(s) selected from among perfumes, insectifuges, rust preventive, mildewproofing agent and bactericide in the form of an inclusion compound in cyclodextrin and a process for the production of the same.
2. Description of the Prior Art
There have been developed various processes for the production of smelling and/or insectifugal synthetic resin products. Some processes comprise applying perfume(s) and/or insectifuge(s)/insecticide onto the surface of a synthetic resin product. Others comprise injecting perfume(s) and/or insectifuge(s)/insecticide into a space in a synthetic resin product or laminating synthetic resin sheets and injecting perfume(s) and/or insectifuge(s)/insecticide between these sheets. It is also possible to mix perfume(s) and/or insectifuge(s)/insecticide with a synthetic resin compound followed by molding the obtained mixture. Perfume(s) and/or insectifuge(s)/insecticide applied on the surface of a synthetic resin product would vaporize so soon that they might not exhibit a persistent effect. On the contrary, those injected into a synthetic resin product would hardly vaporise and might not exhibit an expected effect. Further direct addition of perfume(s) and/or insectifuge(s)/insecticide to a synthetic resin compound is not as effective as it seems. This is because perfumes and/or insectifuges/insecticides are generally so volatile, liable to denature and unstable to heat that it is difficult in practice to mold a mixture of perfume(s) and/or insectifuge(s)/insecticides and a synthetic resin compound into a desired shape. It was further attempted to adsorb desired perfume(s) and/or insectifuge(s)/insecticide(s) by porous inorganic substances such as calcium silicate, zeolite or powdery alumina or porous polymer powders obtained by quenching and artificially grinding synthetic resins with the use of liquid nitrogen during the preparation thereof and to incorporate the obtained composition in a plastic followed by molding. However the desired perfume(s) and/or insectifuge(s)/insecticide(s) are adsorbed merely in pores in each process so that it is necessary to adsorb an excessive amount of them, including those which vaporize at the molding temperature, to give a sufficient amount of the same in molded products, which brings about an additional cost. Thus these processes are not preferable. Further perfume(s) and/or insectifuge(s)/insecticide(s) are not chemically bonded to cyclodextrin but merely adsorbed in pores. Therefore some might be completely removed when heated for molding or might bleed in a short period. Thus these processes are not practical.
Under these circumstances, we have previously invented a process for producing a smelling synthetic resin product which comprises forming an inclusion compound consisting of a perfume included in cyclodextrin, drying and powdering the obtained inclusion compound and mixing the obtained powder with a synthetic resin compound (cf. Japanese Patent No. 1090861).
We have further invented a process for producing an insectifugal and insecticidal film which comprises forming an inclusion compound consisting of an insectifugal and insecticidal agent included in cyclodextrin, drying and powdering the obtained inclusion compound and mixing the obtained powder with a synthetic resin compound followed by molding into a film (cf. Japanese Patent Application No. 188212/1984).
Machines as well as their parts have been packaged by applying rust preventives such as liquid paraffin thereon to wrap them with oil membrane to thereby prevent rusting. The rust preventives such as liquid paraffin are removed at use. Therefore it is required to apply a rust preventive and to remove the same each time a machine is packaged. Conventional oilpapers exhibit some rust preventive effect. However this effect is so insufficient that it is necessary to directly apply a rust preventive on a machine to be packaged. It has been also attempted to package a machine with a paper impregnated with a rust preventive. However this method is available only in a limited range since fine paper pieces entering apertures of a precision machine would cause trouble.
It is a large problem to prevent rust or mildew in silicone and epoxy resins which have been recently employed in semiconductor materials. Since these resins are used in precision electrical instruments, it is impossible to spray or apply rust preventive(s) or mildewproofing agent(s) thereon. Thus these materials are packaged with paper sheets exhibiting a rust preventive and/or mildew-proofing effect.
Also it is sometimes required to prevent rusting in coatings, tackifiers and adhesives. Furthermore those products having a smell or an insectifugal and/or rust preventive effect may be available in a wider range. We have previously invented a product wherein an inclusion compound consisting of a perfume included in cyclodextrin is formed, the inclusion compound thus obtained is mixed with a latex and the mixture is applied on the surface of a tacky substrate (cf. Japanese Patent Laid-Open No. 185372/1982).
A smelling synthetic resin product produced by forming an inclusion compound consisting of a perfume included in cyclodextrin, powdering and drying the obtained inclusion compound and mixing the obtained powder with a synthetic resin compound is much more excellent than those produced by conventional methods. Subsequent studies have proved that not only perfumes but also various substances such as insectifuges, mildew-proofing agents and rust preventives may be formed into an inclusion compound so long as it can be included in cyclodextrin to thereby produce synthetic resin products having the effect of each substance.
However these inclusion compounds consisting of perfumes, insectifuges, mildew-proofing agents or rust preventives included in cyclodextrin can not be used in practice in synthetic resin products of a high molding temperature, i.e. 180.degree. C. or above. Cyclodextrin per se is stable at high temperatures and shows no chemical change so that it is theoretically possible to use it in a synthetic resin of a high molding temperature. However pure cyclodextrin is so expensive that dehydrogenated starches containing cyclodextrin are employed in practice. These dehydrogenated starches are contaminated with reducing sugars which would be denatured and charred when molded at a high temperature.
Although there is no problem in the production of a synthetic resin product having various effects by forming an inclusion compound consisting of perfume(s), insectifuge(s) or rust preventive(s) included in cyclodextrin, drying and powdering the obtained inclusion compound and mixing the obtained powder with a synthetic resin compound on a laboratory scale with the use of pure cyclodextrin, there remains a problem to be solved in the production thereof on an industrial scale.
In addition, the volatility of each substance is somewhat depressed by including the same in cyclodextrin to thereby form an inclusion compound, which allows its effect to persist for a much longer period than with conventional products. However the persistence is somewhat insufficient yet.